Method and apparatus for chemical mechanical polishing of semiconductor substrates

ABSTRACT

Methods and apparatus for processing substrates to improve polishing uniformity, improve planarization, remove residual material and minimize defect formation are provided. In one aspect, a method is provided for processing a substrate having a conductive material and a low dielectric constant material disposed thereon including polishing a substrate at a polishing pressures of about 2 psi or less and at platen rotational speeds of about 200 cps or greater. The polishing process may use an abrasive-containing polishing composition having up to about 1 wt. % of abrasives. The polishing process may be integrated into a multi-step polishing process.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.10/199,444, filed Jul. 19, 2002, now U.S. Pat. No. 6,821,881, whichclaims benefit of U.S. provisional patent application Ser. No.60/308,030, filed Jul. 25, 2001. Each of the aforementioned relatedpatent applications is herein incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Aspects of the invention generally relate to the fabrication ofsemiconductor devices and to chemical mechanical polishing andplanarization of semiconductor devices.

2. Description of the Related Art

Reliably producing sub-half micron and smaller features is one of thekey technologies for the next generation of very large-scale integration(VLSI) and ultra large-scale integration (ULSI) of semiconductordevices. However, as the fringes of circuit technology are pressed, theshrinking dimensions of interconnects in VLSI and ULSI technology hasplaced additional demands on the processing capabilities. The multilevelinterconnects that lie at the heart of this technology require preciseprocessing of high aspect ratio features, such as vias, contacts, lines,and other interconnects. Reliable formation of these interconnects isimportant to VLSI and ULSI success and to the continued effort toincrease circuit density and quality of individual substrates and die.

In order to further improve the current density of semiconductor deviceson integrated circuits, it has become necessary to use conductivematerials having low resistivity and materials having low dielectricconstants (low k, defined herein as having dielectric constants, k, lessthan about 4.0) as insulating layers to reduce the capacitive couplingbetween adjacent interconnects. Increased capacitive coupling betweenlayers can detrimentally affect the functioning of semiconductordevices.

Copper and its alloys have become the materials of choice forsub-quarter-micron interconnect technology because copper has a lowerresistivity than aluminum, (1.7 μΩ-cm compared to 3.1 μΩ-cm foraluminum), a higher current and a higher carrying capacity. Thesecharacteristics are important for supporting the higher currentdensities experienced at high levels of integration and increased devicespeed. Further, copper has a good thermal conductivity and is availablein a highly pure state.

One difficulty in using copper in semiconductor devices is that copperis difficult to etch and achieve a precise pattern. Etching with copperusing traditional deposition/etch processes for forming interconnectshas been less than satisfactory. Therefore, new methods of manufacturinginterconnects having copper-containing materials and low k dielectricmaterials are being developed.

One method for forming vertical and horizontal interconnects is by adamascene or dual damascene method. In the damascene method, one or moredielectric materials, such as the low k dielectric materials, aredeposited and pattern etched to form the vertical interconnects, i.e.,vias, and horizontal interconnects, i.e., lines. Conductive materials,such as copper-containing materials, and other materials, such asbarrier layer materials used to prevent diffusion of copper-containingmaterials into the surrounding low k dielectric, are then inlaid intothe etched pattern. Any excess copper-containing materials and excessbarrier layer material external to the etched pattern such as on thefield of the substrate is then removed.

As layers of materials are sequentially deposited and removed, theuppermost surface of the substrate may become non-planar across itssurface and require planarization. Planarizing a surface, or “polishing”a surface, is a process where material is removed from the surface ofthe substrate to form a generally even, planar surface. Planarization isuseful in dual damascene processes to remove excess deposited materialand to provide an even surface for subsequent levels of metallizationand processing. Planarization may also be used in removing undesiredsurface topography and surface defects, such as rough surfaces,agglomerated materials, crystal lattice damage, scratches, andcontaminated layers or materials.

Chemical mechanical planarization, or chemical mechanical polishing(CMP), is a common technique used to planarize substrates. Inconventional CMP techniques, a substrate carrier or polishing head ismounted on a carrier assembly and positioned in contact with a polishingmedia in a CMP apparatus. The carrier assembly provides a controllablepressure to the substrate urging the substrate against the polishingmedia. The media is moved relative to the substrate by an externaldriving force. Thus, the CMP apparatus effects polishing or rubbingmovement between the surface of the substrate and the polishing mediawhile dispersing a polishing composition to effect both mechanicalactivity and chemical activity.

Conventionally, in polishing copper features, such as dual damascenefeatures, the copper-containing material is polished to the level of thebarrier layer, and then the barrier layer is polished to a level of theunderlying dielectric layer using abrasive polishing solutions. However,such polishing processes often result in uneven removal of materials,such as copper in features and the underlying dielectric layer betweenfeatures, resulting in the formation of topographical defects, such asconcavities or depressions in the features, referred to as dishing, andexcess removal of dielectric material surrounding features, referred toas erosion.

FIG. 1 is a schematic view of a substrate illustrating the phenomenon ofdishing. Conductive lines 11 and 12 are formed by depositing conductivematerials, such as copper or copper alloy, in a feature definitionformed in the dielectric layer 10, typically comprised of silicon oxidesor other dielectric materials. After planarization, a portion of theconductive material in conductive line 12 is depressed by an amount D,referred to as the amount of dishing, forming a concave copper surface.Additionally, dielectric material found around areas having high featuredensities, represented by feature 11, may be excessively eroded comparedto dielectric materials on the field of the substrate from the polishingprocess. Dishing and erosion result in a non-planar surface that impairsthe ability to print high-resolution lines during subsequentphotolithographic steps and detrimentally affects subsequent surfacetopography of the substrate and device formation. Dishing and erosionalso detrimentally affect the performance of devices by lowering theconductance and increasing the resistance of the devices, contrary tothe benefit of using higher conductive materials, such as copper.

An additional difficulty also arises when using low k dielectricmaterial in copper dual damascene formation. Low k dielectric materialsare typically soft, porous, and brittle. Current polishing pressures,about 4 psi or greater, can damage the low k dielectric materialmaterials and form defects in the substrate surface such as filmdelamination.

One solution to reduce dishing and polish low k dielectric material withreduced defect formation is to polish substrates at reduced polishingpressures. However, polishing substrates at reduced pressures oftenresults in less than desirable polishing rates, non-uniform polishing,and less than desirable planarization of the substrate surface. Suchprocess difficulties result in reduced substrate throughput and lessthan desirable polish quality of the substrate surface. Additionally,low polishing pressure processes may be unable to sufficiently removeall of the desired copper materials from a substrate surface such as atthe interface between copper and the barrier layer, which is generallynon-planar. Such copper materials retained on the substrate surface, orresidues, can detrimentally affect device formation, such as creatingshort-circuits within or between devices, reduce device yields, reducesubstrate throughput, and detrimentally affect the polish quality of thesubstrate surface.

Therefore, there exists a need for a method and apparatus thatfacilitates the removal of copper-containing material from the surfaceof a substrate with minimal or reduced dishing and with essentially noresidues remaining after polishing.

SUMMARY OF THE INVENTION

Aspects of the invention generally provide methods for processingsubstrates to improve polishing uniformity, improve planarization,remove residual material and minimize defect formation. In one aspect, amethod is provided for processing a substrate having a conductivematerial and a low dielectric constant material disposed thereonincluding polishing a substrate at a polishing pressure of about 2 psior less and a platen rotational speed of about 200 cps or greater.

In another aspect, a method is provided for processing a substrateincluding polishing a substrate having a low k dielectric materialdisposed thereon at a first polishing pressure of about 2 psi or lessand a platen rotational speed of about 200 cps or greater, and thenpolishing the substrate at a second polishing pressure of about 1.5 psior less.

In another aspect, a method is provided for processing a substratehaving a conductive material disposed thereon in a polishing apparatusincluding polishing the substrate at a first polishing pressure and afirst platen rotational speed and polishing the substrate at a secondpolishing pressure of about 2 psi or less and a second platen rotationalspeed of about 200 cps or greater.

In another aspect, a method is provided for processing a substratecomprising feature definitions formed in a dielectric layer, a barriermaterial deposited on the dielectric layer and in the featuredefinitions, and a conductive material deposited on the barrier materialand filling the feature definitions to a polishing apparatus having oneor more platens and one or more carrier heads including polishing thesubstrate at a polishing pressure of greater than 2 psi and a platenrotational speed between about 26 cps and about 130 cps on a firstplaten, polishing the substrate at a polishing pressure of 2 psi or lessand a platen rotational speed of about 200 cps or greater on the firstplaten, polishing the substrate at a polishing pressure of 2 psi or lessand a platen rotational speed of about 200 cps or greater on a secondplaten, and polishing the substrate at a polishing pressure of greaterthan 2 psi and a platen rotational speed between about 26 cps and about130 cps on the second platen.

In another aspect, a method is provided for processing a substratehaving a conductive material disposed thereon in a polishing apparatusincluding polishing the substrate at a first platen rotational speed ata first polishing pressure of about 2 psi or less and polishing thesubstrate at a second platen rotational speed less than the first platenrotational speed and at a second polishing pressure of about 2 psi orless.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above aspects of the invention areattained and can be understood in detail, a more particular descriptionof the invention, briefly summarized above, may be had by reference tothe embodiments thereof which are illustrated in the appended drawings.

It is to be noted, however, that the appended drawings illustrate onlytypical embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

FIG. 1 is a schematic view of a substrate illustrating the phenomenon ofdishing;

FIG. 2 is a schematic perspective view of a chemical mechanicalpolishing apparatus; and

FIG. 3 is a flowchart illustrating one embodiment of the methoddescribed herein.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In general, aspects of the invention provide methods and apparatus forpolishing substrates with improved polishing uniformity, improvedplanarization, enhanced residual material removal and reduced or minimaldefect formation. The invention will be described below in reference toa planarizing process for the removal of conductive materials, such ascopper-containing materials from a substrate surface by chemicalmechanical polishing (CMP) techniques with polishing media. Chemicalmechanical polishing is broadly defined herein as polishing a substrateby a combination of both chemical and mechanical activity.

The planarization process that can be carried out using chemicalmechanical polishing process equipment, such as the Mirra® CMP Systemavailable from Applied Materials, Inc., of Santa Clara, Calif., as shownand described in U.S. Pat. No. 5,738,574, entitled, “ContinuousProcessing System for Chemical Mechanical Polishing,” the entirety ofwhich is incorporated herein by reference to the extent not inconsistentwith the invention. Although, the CMP process and composition areillustrated utilizing the Mirra® CMP System having rotational platens,any linear or rotational polishing system enabling polishing using themethods described herein, such as the Reflexion™ CMP System availablefrom Applied Materials, Inc., of Santa Clara, Calif., can be used toadvantage. The following apparatus description is illustrative andshould not be construed or interpreted as limiting the scope of theinvention.

FIG. 2 is a schematic perspective view of a chemical mechanicalpolishing system or apparatus 120 for performing the planarizingprocesses and for use with the CMP compositions described herein. Thepolishing apparatus 120 includes a lower machine base 122 with a tabletop 128 mounted thereon and a removable outer cover (not shown). Thetable top 128 supports a series of polishing stations, including a firstpolishing station 125 a, a second polishing station 125 b, a finalpolishing station 125 c, and a transfer station 127. The transferstation 127 serves multiple functions, including, for example, receivingindividual substrates 110 from a loading apparatus (not shown), washingthe substrates, loading the substrates into carrier heads 180, receivingthe substrates 110 from the carrier heads 180, washing the substrates110 again, and transferring the substrates 110 back to the loadingapparatus.

A computer based controller 190 is connected to the polishing system orapparatus 120 for instructing the system to perform one or moreprocessing steps on the system, such as polishing a substrate ortransferring a substrate in the polishing apparatus 120. In oneembodiment, the invention may be implemented as a computerprogram-product for use with a computer system or computer basedcontroller 190. The programs defining the functions of the preferredembodiment can be provided to a computer via a variety of signal-bearingmedia and/or computer readable media, which include but are not limitedto, (i) information permanently stored on non-writable storage media(e.g., read-only memory devices within a computer such as read-onlyCD-ROM disks readable by a CD-ROM or DVD drive; (ii) alterableinformation stored on a writable storage media. (e.g., floppy diskswithin a diskette drive or hard-disk drive); or (iii) informationconveyed to a computer by a communications medium, such as through acomputer or telephone network, including wireless communication. Suchsignal-bearing media, when carrying computer-readable instructions thatdirect the functions of the invention, represent alternative embodimentsof the present invention. It may also be noted that portions of theproduct program may be developed and implemented independently, but whencombined together are aspects described herein.

Each polishing station 125 a–125 c includes a rotatable platen 130having polishing media, such as polishing pads 100 a, 100 b, or 100 cdisposed thereon. The polishing pad is a polishing pad having a durableroughened surface typically composed of microporous polyurethane orpolyurethane mixed with filler. Polishing pads 100 a, 100 b and 100 cmay be embossed or stamped with a pattern to improve distribution ofslurry across the face of the substrate. Polishing pads 100 a, 100 b and100 c may include a hard polishing material, a soft polishing material,or combinations thereof.

A hard polishing material is broadly described herein as a polishingmaterial having a polishing surface of a hardness of about 50 or greateron the Shore D Hardness scale for polymeric materials as described andmeasured by the American Society for Testing and Materials (ASTM),headquartered in Philadelphia, Pa. A suitable hard polishing material isa material comprising the IC-1000, IC-1010, and the IC-1400 polishingpads available from Rodel Inc. of Phoenix, Ariz. (IC-1000 is a productname of Rodel, Inc.)

The polishing pads 100 a, 100 b, and 100 c may also include compositepads of one or more layers, with a surface layer having a hardness ofabout 50 or greater on the Shore D Hardness scale. The composite padsmay have an overall hardness of less than about 50 on the Shore DHardness scale. While the description herein describes the use of the ICseries of pads from Rodel Inc., the invention is equally applicable toall polishing pads having the hardness described herein.

A hard polishing material is broadly described herein as a polishingmaterial having a polishing surface of a hardness of less than about 50on the Shore D Hardness scale for polymeric materials as described andmeasured by the American Society for Testing and Materials (ASTM),headquartered in Philadelphia, Pa. The soft polishing pad may becomposed of a napped poromeric synthetic material, such as a uniformlycompressible material including a polymeric material, i.e., plastic,and/or foam, felt, rubber, or a combination thereof. An example of asoft polishing material is polyurethane impregnated with felt. Anavailable soft polishing pad is included in the Politex or Suba series,i.e., Suba IV, of polishing pads available from Rodel, Inc. (Politex andSuba are tradenames of Rodel, Inc.)

Alternatively, polishing pads 100 a, 100 b, 100 c may be a standardtwo-layer pad in which the upper layer has a durable roughened surfaceand is harder than the lower layer. For example, the upper layer of thetwo-layer pad may be composed of microporous polyurethane orpolyurethane mixed with filler, whereas the lower layer maybe composedof compressed felt fibers leached with urethane. Both the upper andlower layers may be approximately fifty mils thick. A two-layer standardpad, with the upper layer composed of IC-1000 and the lower layercomposed of SUBA-4, is available from Rodel (IC-1000 and SUBA-4 areproduct names of Rodel, Inc.).

In one embodiment of the apparatus, the first polishing station 125 ahas a first hard polishing pad for the first polishing pad 100 adisposed on a platen 130, and the platen 130 disposed thereon is adaptedfor polishing a substrate to remove bulk copper-containing materialdisposed on the substrate. The second polishing station 125 b has asecond hard polishing pad for the second polishing pad 100 b disposed ona platen 130, and the platen 130 disposed thereon is adapted forpolishing a substrate to remove residual copper-containing materialdisposed on the substrate. A third polishing station 125 c having a softpolishing pad for the polishing pad 100 c may be used for a barrierremoval process, such as removing a tantalum containing material, e.g.,tantalum and tantalum nitride, on the substrate and dielectric layerbuffing following the two-step copper removal process.

A rotatable linear platen may be used for the second polishing station125 b. An example of a linear polishing system, and an example of apolishing system having a rotatable polishing pad and a rotatable linearplaten, is more fully described in co-pending U.S. patent applicationSer. No. 09/244,456, filed on Feb. 4, 1999, and incorporated herein byreference to the extent not inconsistent with the invention.Alternatively, a stationary platen or a rotatable or linear platenhaving a stationary media may be used for the first, second, or thirdpolishing stations 125 a, 125 b, and 125 c.

The invention also contemplates the use of an orbital polishing processor orbital polishing platen for the first, second, and/or thirdpolishing stations 125 a, 125 b, and 125 c. A substrate and polishingmedia can be moved in an orbital relative motion in a linear drivesystem where the media is stationary; an example of an apparatus capableof performing the orbital relative motion between the polishing mediaand substrate is the Model 8200, available from Applied Materials Inc.,of Santa Clara, Calif.

Each platen 130 may be a rotatable aluminum or stainless steel platenconnected to a platen drive motor (not shown). The polishing stations125 a–125 c may include a pad conditioner apparatus 140. The padconditioner apparatus 140 has a rotatable arm 142 holding anindependently rotating conditioner head 144 and an associated washingbasin 146. The pad conditioner apparatus 140 maintains the condition ofthe polishing pad so that it will effectively polish the substrates.Each polishing station may include a conditioning station if the CMPapparatus is used with other media configurations.

The polishing stations 125 a–125 c may each have a compositiondelivery/rinse arm 152 that includes two or more supply tubes to provideone or more CMP compositions, cleaning compositions, and/or water to thesurface of the polishing media. The composition delivery/rinse arm 152delivers the one or more chemical slurries in amounts sufficient tocover and wet the entire polishing media. Each compositiondelivery/rinse arm 152 also includes several spray nozzles (not shown)that can provide a high-pressure fluid rinse onto the polishing media atthe end of each polishing and conditioning cycle. Furthermore, two ormore intermediate washing stations 155 a, 155 b, and 155 c may bepositioned between adjacent polishing stations 125 a, 125 b, and 125 cto clean the substrate as it passes from one station to the next.

A rotatable multi-head carousel 160 is positioned above the lowermachine base 122. The carousel 160 includes four carrier head systems170 a, 170 b, 170 c, and 170 d. Three of the carrier head systemsreceive or hold the substrates 110 by pressing them against thepolishing pads 100 disposed on the polishing stations 125 a–125 c. Oneof the carrier head systems 170 a–170 d receives a substrate from anddelivers a substrate 110 to the transfer station 127. The carousel 160is supported by a center post 162 and is rotated about a carousel axis164 by a motor assembly (not shown) located within the machine base 122.The center post 162 also supports a carousel support plate 166 and acover 188.

The four carrier head systems 170 a–170 d are mounted on the carouselsupport plate 166 at equal angular intervals about the carousel axis164. The center post 162 allows the carousel motor to rotate thecarousel support plate 166 and orbit the carrier head systems 170 a–170d about the carousel axis 164. Each carrier head system 170 a–170 dincludes one carrier head 180. A carrier drive shaft 178 connects acarrier head rotation motor 176 (shown by the removal of one quarter ofthe cover 188) to the carrier head 180 so that the carrier head 180 canindependently rotate about its own axis. There is one carrier driveshaft 178 and motor 176 for each head 180. In addition, each carrierhead 180 independently oscillates laterally in a radial slot 172 formedin the carousel support plate 166.

The carrier head 180 performs several mechanical functions. Generally,the carrier head 180 holds the substrate 110 against the polishing pads100, evenly distributes a downward pressure across the back surface ofthe substrate 110, transfers torque from the drive shaft 178 to thesubstrate 110, and ensures that the substrate 110 does not slip out frombeneath the carrier head 180 during polishing operations.

To facilitate control of the system as described above, the controller190 may include a CPU 192 of FIG. 2, which CPU 192 may be one of anyform of computer processors that can be used in an industrial settingfor controlling various chambers and subprocessors. The memory 194 iscoupled to the CPU 192. The memory 194, or computer-readable medium, maybe one or more of the readily available memory such as random accessmemory (RAM), read only memory (ROM), floppy disk, hard disk, or anyother form of digital storage, local or remote. For storing informationand instructions to be executed by the CPU 192.

The support circuits 196 are coupled to the CPU 192 for supporting theprocessor in a conventional manner. These circuits include cache, powersupplies, clock circuits, input/output circuitry and subsystems, and caninclude input devices used with the controller 190, such as keyboards,trackballs, a mouse, and display devices, such as computer monitors,printers, and plotters. Such controllers 190 are commonly known aspersonal computers; however, the present invention is not limited topersonal computers and can be implemented on workstations,minicomputers, mainframes, and supercomputers.

A process, for example, the polishing process described below, isgenerally stored in the memory 194, typically as a software routine. Thesoftware routine may also be stored and/or executed by a second CPU (notshown) that is remotely located from the hardware being controlled bythe CPU 192.

Although the process of the present invention is discussed as beingimplemented as a software routine, some or all of the method steps thatare disclosed therein may be performed in hardware as well as by thesoftware controller. As such, the invention may be implemented insoftware as executed upon a computer system, in hardware as anapplication specific integrated circuit or other type of hardwareimplementation, or a combination of software and hardware.

Chemical Mechanical Polishing Process

Chemical mechanical polishing of substrate surfaces with improvedpolishing uniformity, improved planarization, enhanced residual materialremoval and reduced or minimal defect formation can be achieved by theapplication of increased platen rotational speeds with reduced lowpolishing pressures. In one aspect, copper-containing materials may bepolishing from a substrate surface by a method having low polishingpressures, such as less than about 2 psi, and high platen rotationalspeed, such as greater than about 200 centimeters per second (cps)(e.g., greater than about 150 rpms for a 20 inch rotating platen).Conventional polishing processes use between about 26 cps and about 130cps (e.g., between about 20 rpms and about 100 rpms for a 20 inchrotating platen), and a polishing pressure between about 2 psi and about6 psi.

Polishing at the low polishing pressure and high platen rotational speedhas been observed to be effective in polishing conductive materials fromsubstrate having low dielectric constant (k) materials (i.e., dielectricconstants of about 4 or less.) at removal rates up to about 10000 Å/minwith reduced or minimal damage, such as film delamination, to theunderlying low k dielectric material and effective planarization of bulkcopper materials with minimal dishing.

The low pressure/high platen rotational speed polishing process isperformed by rotating a polishing pad on the platen to provide anaverage platen rotational speed of about 200 cps or greater (about 150rpm or greater), such as between about 200 cps and about 1000 cps (about150 rpm and about 750 rpm). The substrate platen may be rotated at arotational speed between about 200 cps and about 350 cps (about 150 rpmand about 250 rpm). The substrate, which may be disposed in a carrierhead system, may also be rotated at a rotational speed between about 195cps and about 650 cps (between about 150 rpm and about 500 rpm), such asbetween about 400 cps (about 300 rpm) and about 650 cps (about 500 rpm).The substrate is contacted with the polishing pad using a polishingpressure of about 2 psi or less, such as between about 0.1 psi and about1.5 psi.

A polishing composition is applied to the substrate and polishing padduring polishing. The substrate and the polishing pad are typicallyexposed to the polishing composition and contacted for a period of timebetween about 5 seconds and about 30 seconds, such as about 20 seconds.The polishing composition may be supplied to the polishing platen at aflow rate of about 100 ml/min or greater. An example of a suitablepolishing composition includes EPC-5001, which is commercially availablefrom Cabot Corp. of Aurora, Ill. The process and polishing compositionmay be used to remove copper material at a higher removal rate than thebarrier layer material. For example, polishing the substrate surfacewith the EPC-5001 slurry by the process described herein was observed tohave a removal rate ratio, or selectivity, of copper to barrier materialof about 20:1. The composition and process parameters may be chosen toprovide selectivities of copper to barrier of about 10:1 or greater toeffectively remove copper material with reduced or minimal barrier layerremoval.

The polishing composition may be an abrasive-containing polishingcomposition. The abrasive-containing polishing composition may have upto about 1 wt. %, for example, up to about 0.1 wt. %, of abrasives. Inone aspect of the polishing composition, a polishing composition havingbetween about 0.1 wt. % and about 0.5 wt. % may be used.

The low pressure/high platen rotational speed polishing process mayremove copper-containing materials a rate of about 2500 Å/min orgreater, such as between about 3000 Å/min and about 8000 Å/min, forexample 4500 Å/min.

The low pressure/high platen rotational speed polishing process may beintegrated into a multi-step polishing process. In one example, atwo-step process may be used to planarize high overfilling substrates.Overfilling is defined herein as excess deposition of bulk material overfeatures formed in the substrate surface compared to bulk materialdeposited over the field of the substrate. The first polishing stepincludes the low pressure/high platen rotational speed polishing processfor reducing the overfilling thickness with less bulk material removalon the field of the substrate. A second step is then used to removeremaining bulk material with low dishing and erosion. The second stepmay include a second low pressure/high platen rotational speed polishingprocess.

In another example, a three-step polishing process using the lowpressure/high platen rotational speed polishing process as anintermediate step may be used to planarize copper-containing materialson a substrate surface. The first polishing step is used to remove bulkconductive material, such as copper overfill, disposed on the substratesurface, the second polishing step achieves improved planarization ofthe substrate surface, and the third step is used to effect removal ofbulk conductive materials and any residual conductive materials. Abarrier layer polishing composition is used with polishing media toremove the barrier layer typically disposed above a dielectric layerfollowing removal of the conductive material. The two and three-stepprocesses will now be described in relation to polishing a substratesurface.

In another example, a two-step polishing process using the lowpressure/high platen rotational speed polishing process as an initialpolishing step to remove bulk material followed by a low pressure, lowplaten rotational speed polishing step may be performed to planarizecopper-containing materials on a substrate surface.

Examples of substrate that may be polished according to the processesdescribed herein may be formed by a process including etching featuredefinitions in a dielectric layer, depositing a barrier layer materialon the substrate surface and in the feature definitions, and depositinga bulk copper-containing material over the substrate surface to fill thefeature definitions.

As used throughout this disclosure, the phrase “copper-containingmaterial”, “copper” and the symbol Cu are intended to encompass highpurity elemental copper as well as doped copper and copper-based alloys,e.g., doped copper and copper-based alloys containing at least about 80wt. % copper. Bulk copper containing material is broadly defined hereinas copper containing material deposited on the substrate in an amountmore than sufficient to substantially fill features formed on thesubstrate surface. Residual copper containing materials is broadlydefined as any bulk copper containing material remaining after one ormore polishing process steps. Residual copper-containing material caninclude copper, copper alloys, copper oxides, and/or doped copper.

The barrier layer material includes tantalum, tantalum nitride, andderivatives thereof, such as tantalum silicon nitride. The inventiondescribed herein also contemplates the use of other barrier materialsknown or unknown that may used as a barrier with conductive materials,such as copper.

The dielectric layer can comprise any of various dielectric materialsknown or unknown that may be employed in the manufacture ofsemiconductor devices. For example, dielectric materials, such assilicon dioxide, phosphorus-doped silicon glass (PSG),boron-phosphorus-doped silicon glass (BPSG), and carbon-doped silicondioxide, can be employed. The dielectric layer can also comprise lowdielectric constant (k) materials, including fluoro-silicon glass (FSG),polymers, such as polymides, and carbon-containing silicon oxides, suchas Black Diamond™, available from Applied Materials, Inc. of SantaClara, Calif. The openings are formed in interlayer dielectrics byconventional photolithographic and etching techniques. The inventionalso contemplates the use of dielectric materials, known or unknown thatmay be used as dielectric layers in semiconductor fabrication.

While the invention is described in relation to processing steps, thesteps described herein should not be construed or interpreted aslimiting the practice or scope of the invention. For example, thetwo-step and three-step process steps may be performed as part of onecontinuous operation or two or more distinct operations. While thefollowing process described herein illustrates polishing the substrateon two platens, the invention contemplates polishing the substrate bythe process described herein on apparatus having one or more platens.For example, the invention contemplates that the steps may be performedon the same platen or that portions of some process steps may beperformed on multiple platens.

Additionally, while the following processing parameters are generallydescribed for polishing 200 mm substrates, the invention contemplatesmodifying processing parameters to satisfy the requirements forpolishing substrates of different sizes, such as 300 mm substrates, andpolishing on various apparatus, such as orbital motion polishingapparatus. The process described below should be consideredillustrative, and should not be construed or interpreted as limiting thescope of the invention.

In one aspect, a two-step polishing process is provided for processing asubstrate having low k dielectric materials disposed thereon bypolishing a substrate at a polishing pressure of about 2 psi or less andan average platen rotational speed of about 200 cps or greater (about150 rpm or greater) and then polishing the substrate at a polishingpressure of about 1.5 psi or less. The first polishing step is used toremove bulk material, such as bulk copper material, from a substratesurface, and the second polishing step is used to remove residualcopper-containing material from a substrate surface with low dishing anderosion.

The first polishing step includes positioning the substrate on a firstplaten containing a polishing pad 100 disposed on platen 130 inpolishing station 125 a. The polishing pad 100 a is rotated at a platenrotational speed of about 200 cps or greater (150 rpm or greater), suchas between about 200 cps and about 1000 cps (about 150 rpm to about 750rpms) on the rotatable platen 125 a. A platen rotational speed ofbetween about 200 cps and about 350 cps (about 150 rpm to about 250rpms) may be used to polish the substrate surface. The substratedisposed in a carrier head system 170 is rotated at a rotational speedbetween about 195 cps and about 650 cps (between about 150 rpm and about500 rpm), such as between about 400 cps (about 300 rpm) and about 650cps (about 500 rpm). A pressure of about 1.5 psi or less, such asbetween about 0.1 psi and about 1.0 psi, is generally applied betweenthe substrate and the polishing media during the polishing process. Apolishing pressure between about 0.5 psi and about 0.8 psi may be usedfor the first polishing step.

The first polishing composition is supplied to the polishing pad 100 aat a flow rate of about 100 ml/min or greater from a storage mediumdisposed near the CMP apparatus. Typically, a flow rate of between about100 ml/min and about 300 ml/min may be supplied to the polishing pad forpolishing the substrate. Examples of suitable polishing compositions,including abrasive-containing polishing compositions, commerciallyavailable for removing copper-containing material in the first polishingstep include EPC-5003, EPC-5001, and EPC-5306, available from CabotCorp. of Aurora, Ill., and HS-C430-A3, HS-C430-A1, HS-C430-A22,HS-C430-A33, available from Hitachi Chemical Corp. of Japan, of whichEPC-5003 is preferred. The abrasive-containing polishing compositionsmay include up to about 1 wt. % of abrasives, such as between about 0.01wt. % and about 0.1 wt. %.

The substrate and the polishing pad are typically exposed to thepolishing composition and contacted for a period of time sufficient toremove at least a portion or all of the bulk copper-containing materialdisposed thereon. For example, the polishing pad may be exposed to thefirst polishing composition between about 30 seconds and about 180seconds, but may vary depending upon the material being removed, theconcentration of the components of the first polishing composition, andthe amount or thickness of bulk copper-containing material on thesubstrate. The copper-containing material may be removed at a ratebetween about 4000 Å/min and about 8,000 Å/min or any rate to remove thebulk copper-containing materials deposited on the substrate.

The second processing step includes polishing the substrate with asecond polishing composition that may be abrasive-containing orabrasive-free, at a polishing pressure of about 1.5 psi or less. Anabrasive-containing polishing composition may be used to polish thesubstrate at a polishing pressure of about 1.5 psi or less and a platenrotational speed between about 15 cps and about 400 cps (about 10 rpm toabout 300 rpm). An example of polishing parameters for the secondpolishing step includes polishing at 400 cps (300 rpm) and 0.5 psi foran abrasive-containing polishing composition. An example of anabrasive-containing polishing composition is Cabot 5003, commerciallyavailable from Cabot Corp. of Aurora, Ill.

An abrasive-free polishing composition may be used to polish thesubstrate at a polishing pressure of about 1.5 psi or less and a platenrotational speed between about 200 cps to about 1000 cps (about 150 rpmto about 750 rpm). An example of polishing parameters for the secondpolishing step includes polishing at 400 cps (300 rpm) and 0.5 psi foran abrasive-free polishing composition. An example of anabrasive-containing polishing composition is disclosed in U.S. patentapplication Ser. No. 09/544,281, filed on Apr. 6, 2000, entitled,“Abrasive-Free Metal CMP In Passivation Domain”, which is incorporatedherein by reference to the extent not inconsistent with the claimedaspects and disclosure herein.

The substrate and the polishing media are typically exposed to thesecond polishing composition for a period of time sufficient to removethe residual copper-containing materials disposed thereon and providefor overpolishing of the substrate surface to further remove defectsformed thereon. For example, the polishing media may be exposed to thesecond polishing composition between about 30 seconds and about 180seconds, but may vary depending upon the material being removed, theconcentration of the components of the second polishing composition, andthe amount or thickness of residual copper material on the substrate.The copper-containing material is removed at a rate up to about 2000Å/min or less, such as between about 500 Å/min and about 2000 Å/min.Following copper-containing material removal, the substrate may bepolished to remove the barrier layer and cleaned as described herein.

In another example, a two-step polishing process is provided forprocessing a substrate having low k dielectric materials disposedthereon by polishing a substrate at a polishing pressure of about 2 psior less and an average platen rotational speed of about 200 cps orgreater (about 150 rpm or greater) and then polishing the substrate at apolishing pressure of about 2 psi or less and an average platenrotational speed of about 100 cps or less (about 75 rpms or less). Thefirst polishing step is used to remove bulk material, such as bulkcopper material, from a substrate surface, and the second polishing stepis used to remove residual copper-containing material from a substratesurface with low dishing and erosion. The pressure may remain constantduring both polishing processes. Alternatively, the second pressure maybe less than the first pressure as described herein for a two-steppolishing process.

The first polishing step includes positioning the substrate on a firstplaten containing a polishing pad 100 disposed on platen 130 inpolishing station 125 a. The polishing pad 100 a is rotated at a platenrotational speed of about 200 cps or greater (150 rpm or greater), suchas between about 200 cps and about 1000 cps (about 150 rpm to about 750rpms) on the rotatable platen 125 a. A platen rotational speed ofbetween about 200 cps and about 500 cps (about 150 rpm to about 375rpms), such as between about 200 cps and about 350 cps (about 150 rpm toabout 250 rpms) may be used to polish the substrate surface. Thesubstrate disposed in a carrier head system 170 is rotated at arotational speed between about 195 cps and about 650 cps (between about150 rpm and about 500 rpm), such as between about 400 cps (about 300rpm) and about 650 cps (about 500 rpm).

A pressure of about 2.0 psi or less, such as about 1.5 psi or less, forexample, between about 0.1 psi and about 1.0 psi, is generally appliedbetween the substrate and the polishing media during the polishingprocess. A polishing pressure between about 0.5 psi and about 0.8 psimay be used for the first polishing step.

The first polishing composition is supplied to the polishing pad 100 aat a flow rate of about 100 ml/min or greater from a storage mediumdisposed near the CMP apparatus. Typically, a flow rate of between about100 ml/min and about 300 ml/min may be supplied to the polishing pad forpolishing the substrate. Examples of suitable polishing compositions,including abrasive-containing polishing compositions, commerciallyavailable for removing copper-containing material in the first polishingstep include EPC-5003, EPC-5001, and EPC-5306, available from CabotCorp. of Aurora, Ill., and HS-C430-A3, HS-C430-A1, HS-C430-A22,HS-C430-A33, available from Hitachi Chemical Corp. of Japan, of whichEPC-5003 is preferred. The abrasive-containing polishing compositionsmay include up to about 1 wt. % of abrasives, such as between about 0.1wt. % and about 0.5 wt. %.

The substrate and the polishing pad are typically exposed to thepolishing composition and contacted for a period of time sufficient toremove at least a portion or all of the bulk copper-containing materialdisposed thereon. For example, the polishing pad may be exposed to thefirst polishing composition between about 30 seconds and about 180seconds, but may vary depending upon the material being removed, theconcentration of the components of the first polishing composition, andthe amount or thickness of bulk copper-containing material on thesubstrate. The copper-containing material may be removed at a ratebetween about 4000 Å/min and about 8,000 Å/min or any rate to remove thebulk copper-containing materials deposited on the substrate.

The second processing step includes polishing the substrate with asecond polishing composition that may be abrasive-containing orabrasive-free, at a second polishing pressure of about 2.0 psi or lessand a second platen rotational speed less than the first rotationalspeed.

The polishing pad 100 a is rotated at a platen rotational speed of about100 cps or less (75 rpm or greater), such as between about 50 cps andabout 100 cps (about 37 rpm to about 75 rpms) on the rotatable platen125 a. The substrate disposed in a carrier head system 170 is rotated ata rotational speed between about 195 cps and about 650 cps (betweenabout 150 rpm and about 500 rpm), such as between about 400 cps (about300 rpm) and about 650 cps (about 500 rpm). The second polishingpressure may be maintained at the first polishing pressure or may beless than the first polishing pressure. An abrasive-containing polishingcomposition or an abrasive-free polishing composition may be used topolish the substrate during this two-step process.

The substrate and the polishing media are typically exposed to thesecond polishing composition for a period of time sufficient to removethe residual copper-containing materials disposed thereon and providefor overpolishing of the substrate surface to further remove defectsformed thereon. For example, the polishing media may be exposed to thesecond polishing composition between about 30 seconds and about 180seconds, but may vary depending upon the material being removed, theconcentration of the components of the second polishing composition, andthe amount or thickness of residual copper material on the substrate.The copper-containing material is removed at a rate up to about 2000Å/min or less, such as between about 500 Å/min and about 2000 Å/min.Following copper-containing material removal, the substrate may bepolished to remove the barrier layer and cleaned as described herein.

FIG. 3 is a flow chart illustrating one embodiment of a process forutilizing the apparatus described herein to remove materials in athree-step planarization process. A substrate is positioned on a firstplaten containing an abrasive-free polishing pad and a first polishingcomposition is supplied to the polishing pad 100 at step 200. Bulkcopper containing materials are then removed from the surface of thesubstrate by polishing the substrate at a first polishing pressure and afirst platen rotational speed at step 210. The substrate is thenpolished at a second polishing pressure less than the first polishingpressure and a second platen rotational speed greater than the firstplaten rotational speed to planarize the polished material at step 220.The substrate is then transferred to a second polishing platen at step230. The substrate is polished at a second platen rotational speedgreater than the first platen rotational speed at step 240. Thesubstrate is then polished at a third polishing pressure greater thanthe second polishing pressure and a third platen rotational speed lessthan the second platen rotational speed at step 250. The substrate maythen be positioned at a third platen in step 260 and polished to removethe barrier layer and to be cleaned at step 270.

In the first polishing step of the three-step polishing process, thesubstrate is positioned on a first platen containing a polishing pad 100disposed on platen 130 in polishing station 125 a. The carousel 160positions the substrate in contact with the polishing pad 100 a, and thesubstrate and the polishing pad move relative to one another with afirst polishing composition distributed between to effect chemical andmechanical activity on the substrate, and then the substrate istypically removed from contact with the polishing pad 100 a.

The polishing pad 100 a is rotated to provide an average platenrotational speed less than about 130 cps (less than about 100 rpm for a20 inch platen), such as between about 26 cps and about 130 cps (about20 rpm and about 100 rpm), on the rotatable platen 125 a. The substrateplaten may be rotated at a rotational speed between about 65 cps (about50 rpms) and about 130 cps (about 100 rpm). The substrate disposed in acarrier head system 170 is rotated at a rotational speed between about26 cps (20 rpm) and about 130 cps (100 rpm). A pressure between about 2psi and about 6 psi is generally applied between the substrate and thepolishing media during the polishing process.

The first polishing composition is supplied to the polishing pad 100 aat a flow rate of about 100 ml/min or greater from a storage mediumdisposed near the CMP apparatus. Typically, a flow rate of between about100 ml/min and about 300 ml/min may be supplied to the polishing pad forpolishing the substrate. Examples of suitable polishing compositions,including abrasive-containing polishing compositions, commerciallyavailable for removing copper-containing material in the first polishingstep include EPC-5003, EPC-5001, and EPC-5306, available from CabotCorp. of Aurora, Ill., and HS-C430-A3, HS-C430-A1, HS-C430-A22,HS-C430-A33, available from Hitachi Chemical Corp. of Japan, of whichEPC-5001 is preferred.

The substrate and the polishing pad are typically exposed to thepolishing composition and contacted for a period of time sufficient toremove at least a portion or all of the bulk copper-containing materialdisposed thereon. For example, the polishing pad may be exposed to thefirst polishing composition between about 30 seconds and about 180seconds, but may vary depending upon the material being removed, theconcentration of the components of the first polishing composition, andthe amount or thickness of bulk copper-containing material on thesubstrate. The copper-containing material may be removed at a ratebetween about 4000 Å/min and about 8,000 Å/min or any rate to remove thebulk copper-containing materials deposited on the substrate.

In the second polishing step, the substrate is then polished using apolishing pressure less than the first polishing pressure and at aplaten rotational speed greater than the first platen rotational speed.The polishing pad 100 a is rotated to provide an average platenrotational speed of about 200 cps or greater (about 150 rpm or greater),such as between about 200 cps and about 1000 cps (about 150 rpm andabout 750 rpm). The substrate platen may be rotated at a rotationalspeed between about 150 rpm and about 250 rpm. The substrate disposed ina carrier head system 170 may also be rotated at a rotational speedbetween about 195 cps and about 650 cps (between about 150 rpm and about500 rpm), such as between about 400 cps (300 rpm) and about 650 cpsabout (500 rpm). The substrate is polished using a polishing pressure ofabout 2 psi or less, such as between about 0.5 psi and about 1.5 psi.

The first polishing composition and flow rates may be used to polish thesubstrate in the second polishing step. The substrate and the polishingpad are typically exposed to the polishing composition and contacted fora period of time between about 5 seconds and about 30 seconds, such asabout 20 seconds. The copper-containing material may be removed at arate between about 150 Å/min or less, such as between about 50 Å/min andabout 100 Å/min.

The substrate may then be positioned on a second platen containing asecond polishing pad 100 b, and includes positioning the substrate onthe polishing pad 100 b at polishing station 125 b. A second polishingcomposition is supplied to the polishing pad 100 b. The carousel 160positions the substrate in contact with the polishing pad 100 b, and thesubstrate and the polishing pad 100 b move relative to one another withthe composition distributed between to effect chemical and mechanicalactivity on the substrate, and then the substrate is typically removedfrom contact with the polishing pad 100 b. Any remaining bulkcopper-containing materials and residual copper-containing materials arethen removed from the surface of the substrate on the second platen.

The second polishing step is again performed on the second platen asdescribed for the first polishing platen. The polishing pad 100 a isrotated to provide an average platen rotational speed of about 200 cpsor greater (about 150 rpm or greater), such as between about 200 cps andabout 1000 cps (about 150 rpm and about 750 rpm) and a polishingpressure of about 2 psi or less, such as between about 0.5 psi and about1.5 psi. The substrate disposed in a carrier head system 170 may also berotated at a rotational speed between about 195 cps and about 650 cps(between about 150 rpm and about 500 rpm), such as between about 400 cps(about 300 rpm) and about 650 cps (about 500 rpm). The second polishingcomposition may be supplied to the polishing platen at a flow rate ofabout 100 ml/min or greater. The second polishing composition maycomprise the first polishing composition, for example, EPC-5001,available from Cabot Corp. of Aurora, Ill.

The substrate and the polishing pad are typically exposed to thepolishing composition and contacted for a period of time between about 5seconds and about 30 seconds, such as about 20 seconds. Thecopper-containing material may be removed at a rate between about 150Å/min or less, such as between about 50 Å/min and about 100 Å/min.

The substrate may then polished using the third polishing step having apolishing pressure greater than the second polishing pressure and at aplaten rotational speed less than the second platen rotational speedusing a second polishing composition. The third polishing step providesan average platen rotational speed of less than about 130 cps (less thanabout 100 rpm), such as between about 26 cps and about 130 cps (about 20rpm to about 100 rpm) and a polishing pressure of about 2 psi orgreater, such as between about 2 and about 6 psi. The substrate disposedin a carrier head system 170 is rotated at a rotational speed betweenabout 65 cps (about 50 rpms) and about 155 cps (about 120 rpms). Thesecond polishing composition may be supplied to the polishing platen ata flow rate of about 100 ml/min or greater.

The processing parameters of the third polishing step may be modifiedbased upon the use of either an abrasive-containing or abrasive-freesecond polishing composition. For example, an abrasive-free polishingcomposition may be used to polish the substrate at a polishing pressureof about 3 psi and a platen rotational speed of about 80 cps (about 60rpm). An abrasive-containing polishing composition may be used to polisha substrate at a polishing pressure of about 2 psi and about 130 cps(about 100 rpm).

The substrate and the polishing media are typically exposed to thesecond polishing composition in the third polishing step for a period oftime sufficient to remove residual copper-containing materials disposedthereon and provide for overpolishing of the substrate surface tofurther remove defects formed thereon. For example, the polishing mediamay be exposed to the second polishing composition between about 30seconds and about 180 seconds, but may vary depending upon the materialbeing removed, the concentration of the components of the secondpolishing composition, and the amount or thickness of residual coppermaterial on the substrate. The copper-containing material is removed ata rate up to about 2000 Å/min or less.

It has been observed that the two-step and three-step polishingprocesses described above reduce dishing of the copper-containingmaterial, reduce the presence of residual materials, and improvepolishing uniformity and planarization of the substrate surface duringchemical mechanical polishing of the substrate surface.

Following conductive material removal, the barrier layer may beselectively removed in relation to the copper and dielectric materials,i.e., remove the barrier layer at higher removal rates than the copperor dielectric materials, or the barrier layer composition maynon-selectively remove the copper, barrier, and dielectric materials atapproximately equal rates.

The substrate may then be rinsed on following barrier layer removal toremove surface defects and particles adhering to the substrate surface.The above processing steps may be performed on the same apparatus or maybe performed on more than one apparatus. Additionally, the substrate maybe transferred to a cleaning module or subjected to an in situ cleaningprocess to also remove surface defects, such as oxides that form on thecopper-containing material.

Barrier layer removal may be performed on the third platen bypositioning the substrate on a third platen containing a polishing pad100 c, and typically includes positioning a substrate on the thirdpolishing pad 100 c disposed on platen 130 in polishing station 125 c,supplying a barrier removal polishing composition to the polishing pad100 and contacting the polishing media and substrate to remove barrierlayer materials, such as tantalum containing materials, from the surfaceof the substrate by a polishing process on the substrate.

The polishing pad 100 c is rotated at a rate between about 65 cps (about50 rpms) and about 155 cps (about 120 rpms) for a polishing pad disposedon a rotatable platen. The substrate disposed in a carrier head system170 is rotated at a rate between about 65 cps (about 50 rpms) and about155 cps (about 120 rpms). The polishing pad and substrate are rotated inthe same direction to provide a relative motion between one another. Apressure between about 0.5 psi and about 6 psi between the substrate andthe polishing pad 100 c is used to provide mechanical activity to thepolishing process.

The barrier layer polishing composition is delivered or supplied to thepolishing pad at a flow rate of about 100 ml/min or greater from astorage medium disposed near the CMP apparatus. Examples of suitablepolishing compositions, including abrasive-containing polishingcompositions and abrasive-free polishing compositions, commerciallyavailable for removing barrier layer material include HS-T605 andHS-T505, available from Hitachi Chemical Corp. of Japan. An example of asuitable polishing composition in disclosed in U.S. Provisional PatentApplication No. 60/305,314, filed on Jul. 13, 2001, entitled, “DualReduced Agents For Optimum Barrier Removal In Chemical MechanicalPolishing”, which is incorporated herein by reference to the extent notinconsistent with the claimed aspects and disclosure herein. Thesubstrate and the polishing pad are typically exposed to the polishingcomposition and contacted for a period of time sufficient to remove thebarrier layer material, for example between about 60 seconds and about180 seconds. The barrier layer materials may be removed at a rate up toabout 1200 Å/min.

Optionally, a cleaning solution may be applied to each of the polishingpads during or subsequent each of the polishing process to removeparticulate matter and spent reagents from the polishing process as wellas help minimize metal residue deposition on the polishing pads anddefects formed on a substrate surface. An example of a suitable cleaningsolution is Electra Clean™ commercially available from AppliedMaterials, Inc. of Santa Clara, Calif.

EXAMPLE

An example of a two-step copper polishing process according to aspectsof the invention described herein is as follows. A substrate including alow k dielectric material, such as Black Diamond™ from AppliedMaterials, Inc. of Santa Clara, Calif., with feature definitions formedtherein, a tantalum barrier layer deposited on the dielectric layer andin the feature definitions formed therein, and a copper-containing layerdeposited on the barrier layer and filling the feature definitionsformed therein is provided to the polishing apparatus disclosed above.

The substrate is positioned over an IC-1000 polishing pad of a firstplaten, and a first polishing composition of Cabot EPC-5001 is deliveredto the polishing pad at a flow rate of about 200 ml/min. The platen isrotated at a platen rotational speed of about 800 cps (about 600 rpm)and a pressure of about 0.5 psi is applied between a substrate andpolishing pad. The substrate is polished at this platen rotational speedand pressure for about 60 seconds at a rate of about 5000 Å/minute toremove the bulk copper material.

The substrate is then positioned over an IC-1000 polishing pad on asecond platen, and a second polishing composition of Cabot EPC-5001 isdelivered to the polishing pad at a flow rate of about 200 ml/min. Theplaten is then rotated at a platen rotational speed of about 400 cps(about 300 rpm) and at a polishing pressure of about 0.5 psi. Thesubstrate is polished at this platen rotational speed and pressure forabout 60 seconds at a rate of about 1500 Å/minute to remove the residualcopper material. Alternatively, an abrasive-free polishing compositionmay be used at a platen rotational speed of about 400 cps (about 300rpm) and at a polishing pressure of about 0.5 psi to remove residualcopper material.

The substrate is then transferred to a third platen having a Politexpolishing pad disposed thereon, and a barrier layer polishingcomposition is delivered to the polishing pad to remove the barrierlayer material and planarize the surface of the substrate. The barrierlayer polishing composition is provided at a flow rate of about 200ml/min, the platen is rotated at a speed of about 120 cps (about 93rpm), the carrier head is rotated at a speed of about 110 cps (about 87rpms), and a pressure of about 2 psi is applied between a substrate andpolishing pad. The substrate is then polished for a requisite amount oftime at a rate up to about 1200 Å/minute to sufficiently remove thebarrier layer materials. An Electra Clean™ solution is then used toclean the substrate surface following the polishing processes.

An example of a three-step polishing process according to aspects of theinvention described herein is as follows. A substrate including adielectric material with feature definitions formed therein, a tantalumbarrier layer deposited on the dielectric layer and in the featuredefinitions formed therein, and a copper-containing layer deposited onthe barrier layer and filling the feature definitions formed therein isprovided to the polishing apparatus disclosed above.

The substrate is positioned over an IC-1000 polishing pad of a firstplaten, and a first polishing composition of Cabot EPC-5001 is deliveredto the polishing pad at a flow rate of about 200 ml/min. The platen isrotated at a platen rotational speed of about 130 cps (100 rpm) and apressure of about 5.5 psi is applied between a substrate and polishingpad and copper material is removed. The platen is then rotated at arotational speed of about 200 cps (150 rpm) and at a polishing pressureof about 1 psi while continuing delivery of the first polishingcomposition to planarize the surface.

The substrate is then positioned over an IC-1000 polishing pad on asecond platen, and a second polishing composition of Cabot EPC-5001 isdelivered to the polishing pad at a flow rate of about 200 ml/min. Theplaten is then rotated at a platen rotational speed of about 200 cps(about 150 rpm) and at a polishing pressure of about 1 psi to removecopper material. The platen is then rotated at a platen rotational speedof about 130 cps (about 100 rpm) and a pressure of about 2 psi isapplied between a substrate and polishing pad while continuing deliveryof the second polishing composition. The substrate is then polished fora requisite amount of time at a rate of less than about 2000 Å/minuteand about 8,000 Å/minute to sufficiently remove the residual coppermaterial.

The substrate is then transferred to a third platen having a Politexpolishing pad disposed thereon, and a barrier layer polishingcomposition is delivered to the polishing pad to remove the barrierlayer material and planarize the surface of the substrate. The barrierlayer polishing composition is provided at a flow rate of about 200ml/min, the platen is rotated at a speed of about 120 cps (93 rpm), thecarrier head is rotated at a speed of about 110 cps (about 87 rpms), anda pressure of about 2 psi is applied between a substrate and polishingpad. The substrate is then polished for a requisite amount of time at arate up to about 1200 Å/minute to sufficiently remove the barrier layermaterials. An Electra Clean™ solution is then used to clean thesubstrate surface following the polishing processes.

In an alternative method of the three-step polishing process, thesubstrate is positioned over an IC-1000 polishing pad of a first platen,the platen is rotated at a rotational speed of about 130 cps (about 100rpm) and a pressure of about 5.5 psi is applied between a substrate andpolishing pad, and a first polishing composition, such as abrasivecontaining Cabot EPC-5001, is delivered to the polishing pad at a flowrate of about 200 ml/min. The platen is then rotated at a rotationalspeed of about 260 cps (about 200 rpm) and at a polishing pressure ofabout 1 psi while continuing delivery of a second polishing compositionof Cabot EPC-5003 at 200 ml/min.

The substrate is then positioned over an IC-1000 polishing pad on asecond platen, and an abrasive free polishing composition is deliveredto the polishing pad at a flow rate of about 200 ml/min. The abrasivefree polishing composition may be used to polish the substrate at 260cps (200 rpm) and 1 psi. Alternatively, an abrasive polishingcomposition, such as Cabot EPC-5003, may be used to polish the substrateat a platen rotational speed of 130 cps (100 rpm) and 1.5 psi. Theplaten is then rotated at a platen rotational speed of about 130 cps(about 100 rpm) and a pressure of about 2 psi is applied between asubstrate and polishing pad while continuing delivery of a thirdpolishing composition, such as EPC-5001. The substrate is then polishedfor a requisite amount of time at a rate of less than about 2000Å/minute and about 8,000 Å/minute to sufficiently remove the residualcopper material.

While the foregoing is directed to embodiments of the present invention,other and further embodiments of the invention may be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

1. A method for processing a substrate having a conductive materialdisposed thereon in a polishing apparatus, comprising: polishing theconductive material at a first polishing pressure of about 1.5 psi orless, a first carrier head rotational speed of about 195 cps or greater,and a first platen rotational speed of about 200 cps or greater on afirst platen; and polishing the conductive material at a secondpolishing pressure of about 1.5 psi or less, a second carrier headrotational speed less than the first carrier head rotational speed, anda second platen rotational speed less than the first rotational speed ona second platen.
 2. The method of claim 1, wherein the first polishingpressure is between about 0.2 psi and about 1.0 psi and the secondpolishing pressure is between about 0.2 psi and about 1.0 psi.
 3. Themethod of claim 1, wherein the first platen rotational speed is betweenabout 200 cps and about 500 cps and the second platen rotational speedis between about 50 cps and about 100 cps and the first carrier headrotational speed of between about 195 cps and about 650 cps and thesecond carrier head rotational speed of between about 65 cps and about155 cps.
 4. The method of claim 1, further comprising polishing thebarrier material at a third platen.
 5. The method of claim 1, whereinthe conductive material comprises copper, doped copper, copper alloys,or combinations thereof and the barrier material comprises tantalum,tantalum nitride, or combinations thereof.
 6. The method of claim 1,wherein polishing the substrate at the second polishing step comprisespolishing with an abrasive polishing composition having up to about 1wt. % of abrasives.
 7. A method for processing a substrate comprisingfeature definitions formed in a dielectric layer, a barrier materialdeposited on the dielectric layer and in the feature definitions, and aconductive material deposited on the barrier material and filling thefeature definitions to a polishing apparatus having one or more platensand one or more carrier heads, comprising: polishing the substrate at apolishing pressure of greater than 2 psi and a platen rotational speedbetween about 26 cps and about 130 cps on a first platen; polishing thesubstrate at a polishing pressure of 1.5 psi or less and a platenrotational speed of about 200 cps or greater on the first platen;polishing the substrate at a polishing pressure of 1.5 psi or less and aplaten rotational speed of about 200 cps or greater on a second platen;and polishing the substrate at a polishing pressure of greater than 2psi and a platen rotational speed between about 26 cps and about 130 cpson the second platen.
 8. The method of claim 7, further comprisingpolishing the substrate to remove the barrier layer.
 9. The method ofclaim 7, wherein the substrate is polished at a polishing pressure ofabout 5.5 psi and a platen rotational speed of about 130 cps (about 100rpm) and then polished at a polishing pressure of about 1 psi and aplaten rotational speed of about 200 cps on the first platen.
 10. Themethod of claim 7, wherein the substrate is polished at a polishingpressure of about 1 psi and a platen rotational speed of about 200 cpsand then is polished at a polishing pressure of about 5.5 psi and aplaten rotational speed of about 130 cps on the second platen.
 11. Themethod of claim 7, wherein the substrate is polished at a polishingpressure of about 1 psi and a platen rotational speed of about 200 cpsand then is polished at a polishing pressure of about 3 psi and a platenrotational speed of about 60 rpm with an abrasive free polishingcomposition on the second platen.
 12. The method of claim 7, wherein thesubstrate is polished at a polishing pressure of about 1 psi and aplaten rotational speed of about 200 cps and then is polished at apolishing pressure of about 2 psi and a platen rotational speed of about130 cps with an abrasive polishing composition on the second platen. 13.The method of claim 12, wherein the abrasive polishing compositionincludes up to about 1.0 wt. % abrasives.
 14. The method of claim 7,wherein the conductive material comprises copper, doped copper, copperalloys, or combinations thereof, and the barrier layer comprisestantalum, tantalum nitride, or combinations thereof.
 15. A method forprocessing a substrate having a conductive material disposed thereon ina polishing apparatus, comprising: polishing the substrate at a firstplaten rotational speed between about 200 cps and about 500 cps at afirst polishing pressure between about 0.2 psi and about 1.0 psi; andpolishing the substrate at a second platen rotational speed less thanthe first platen rotational speed and at a second polishing pressurebetween about 0.2 psi and about 1.0 psi, wherein the second platenrotational speed is about 100 cps or less, wherein polishing thesubstrate at the first platen rotational speed and the second platenrotational speed are performed on the same platen.
 16. The method ofclaim 15, wherein the second platen rotational speed is between about 50cps and about 100 cps.
 17. The method of claim 15, wherein the polishingthe substrate at the first platen further comprises a first carrier headrotational speed of between about 195 cps and about 650 cps and thepolishing the substrate at the second platen further comprises a secondcarrier head rotational speed of between about 65 cps and about 155 cps.18. The method of claim 15, wherein the conductive material comprisescopper, doped copper, copper alloys, or combinations thereof.
 19. Themethod of claim 15, wherein polishing the substrate at the secondpolishing comprises polishing with an abrasive polishing compositionhaving up to about 1 wt. % of abrasives.
 20. The method of claim 15,wherein the substrate further comprises a low k dielectric material, abarrier material disposed on the low k dielectric material, and theconductive material is disposed on the barrier material.
 21. The methodof claim 20, further comprising polishing the barrier material.
 22. Themethod of claim 20, the barrier material comprises tantalum, tantalumnitride, or combinations thereof.